1. Field of the Invention
The present invention relates to vehicular head-lighting systems, and more particularly, to vehicular head-lighting systems employed in vehicles such as automobiles.
2. Description of the Related Art
Vehicular lamp systems configured to dynamically control light distribution so as to match the non-illuminated areas to cars running ahead, or to oncoming cars, in front of a driver's vehicle (hereinafter, generically referred to as “frontward vehicles”) have been proposed. This sort of light distribution control is sometimes referred to as adaptive driving beam (ADB) control. In ADB control, an appropriate light distribution pattern is selected based on results of detecting frontward vehicles through vehicle detection means such as a camera, or on the traveling state of the driver's vehicle. The vehicular lamp is controlled so as to form the selected light distribution pattern. The process thus is reiterated in a series, with the result that the light distribution pattern is changed as the situation requires. Automatic adjustment of light distribution in this way is beneficial both in securing an extensive field of view ahead of the driver's vehicle, and in reducing glare toward frontward vehicles.
However, depending on the motoring venue, automatic switching of light distribution patterns by means of ADB control can occur with remarkable frequency. Excessively frequent change in light distribution could cause it to be felt in the driver's vehicle or the frontward vehicle as a worry or other sense that something is wrong.
In particular, if high-beam/low-beam switching is iterated to excess, because such switching ordinarily accompanies the high beam indicator turning on and off, to the driver it can look as though the indicator is flashing inexplicably. Despite the fact that this flashing of the indicator is the result of normal light distribution switching in response to the circumstances, because it might make the driver misunderstand that the flashing is being caused by some sort of abnormality and feel uneasy, it is unwelcome.